Cody Lovejoy Ramsey Doany Kyle Jones

2.1 RFID INVENTORY SYSTEM

PROBLEM STATEMENT

• The International Space Station (ISS)

• Power Consumption

• Current RFID Inventory System• Inefficient• Wasteful

WHAT IS RFID?

• Radio Frequency Identification• Credit Cards• Key Cards• Inventory

• Passive• RLC Circuit• Induction• Frequency• Antenna

• Microchip• Data (128 bit)• Random Number Generators• Handle• Response Delay Time

RFID SYSTEMTag Reader

• Antenna• Transceiver• Computer/Software• Modulation/

Coding• Demodulation/

Decoding

CURRENT OPERATION (TDM)

Tag Power-Up/Search Query

Load 2Q-1 Bit RNG

Decrement/Search Query

Handle Number

ACK

Tag Data

ACK/Tag Power-Down

PROPOSAL & REQUIREMENTS• TDM CDMA/DSSS• Conform to Class I Gen. II Specs• 75% reduction in power consumption• Read 5 tags simultaneously• 80% Accuracy (for initial

prototype)• Alien ALR 9900+• Software simulation• Hardware Simulation (stretch goal)

CDMA/DSSS• Code Division Multiple Access (CDMA)

• Multiplexing

• Multiple users occupy channel simultaneously

• Orthogonal spreading codes

• Direct Sequence Spread Spectrum

• Spreading signal bandwidth

• Increase transmission speed

• Bit redundancy

CDMA-BASED RFID SYSTEM

• Single “beckoning” signal• All tags respond simultaneously (128 bit EPC data)• Reader receives summation of all tag transmissions• Reader demodulates/decodes signal

Tag Power-Up/Query

Tag Data

• 1 transmission (any number of tags)

• 98.5% less power consumption

• “Brute force” method

• At least 69 transmissions (5 tags, assuming no collisions)

• Reader constantly scanning

SUPERIORITY OF CDMA-BASED SYSTEM

TDM-Based System CDMA-Based System

BUDGET• $600

• Alien RFID hardware, testing equipment, and software provided by Texas State University

• None of budget was used

CONSTRAINTS• Technical

• Limited number of orthogonal spreading codes

• Non-Technical

• Proprietary design/Industry secrets

• Manufacturability

• Economies of scale

SYSTEM OUTLINE• 5 simulated tags

• 8 bits of data

• Spreading code (Processing Gain of 16)

• Transmission

• Bit streams summed (128 bits total)

• ASK modulation

• Reception

• ASK demodulation

• Re-application of spreading codes

TOOLSAlien RFID Development System

ReaderTags

Oscilloscope & Spectrum AnalyzerCharacterization of RFID Signals

RF Signal GeneratorTransmission

HackRFReception

SOFTWARE DESIGN & DEMO

FUNCTION GENERATORDATASW

MODSW

DEMOD

DATA&

AIC

HARDWARE DESIGN & DEMO

FUNCTION GENERATORHackRF

DATA

ADAPTIVE INTERFERENCE CANCELLATION

Apply first despreading code to extract first signalDecode first signalSubtract first signal from conglomerate received signalApply second despreading code to extract next signalDecode second signalSubtract second signal from conglomerate signalContinue until all signals are decodedUsed in Software Simulation

RESULTS• Proof of CDMA RFID concept

• Addition of adaptive interference cancellation

• Proof of reduction in power consumption

• 92%+ decrease

• Feasibility

THE FUTURE• Greater error control capability

• Coherent PSK

• Adaptive Interference Cancellation (Hardware)

• Class I Gen III tags with CDMA capability

• Use in remote and/or handheld applications

• Adding Locating capability

AT OUR BOOTH• Software Simulation

• With adaptive interference calculation

• Hardware Simulation

• Transmitter

• CDMA Encoding

• Modulated waveform transmission

• Receiver

• Modulated waveform reception

• CDMA Decoding

• Mathematical proof of claims

QUESTIONS?